How much score or GPA in Btech is required to satisfy interviewer after writing gate and isit better to start preparingfor gate from 2ndyear

Dear Sai Chandra
According to my prior experience,  you need at least 7.5 CGPA and without extra curricular activities it's if no use.  So if you want good score and good job as you've mentioned above you need to not only work on CGPA but also on the extra things.
All the best.

Yes it is well advised to start preparing from Secind last year itself for GATE Prpeparation as well as PSU recruitment. You need to appear for ample mock exams and analyse your mistakes to score well.

You should be havibg sufficient Technical knowledge to impress the interviewer alobgwith CGPA of Minimum 8.5/10.

Above all a good resume including extracurricular and cocurricular activity, Volunteer experience, decent academic background is recommended to get through Mtech or PSU recruitment via GATE.